Apple Logic Pro 7.2 User Manual

Page 42

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42

Chapter 1

Control Surface Setup

If the message does not contain Lo7 or Hi7 placeholders, an incoming value of 1 is
assumed. This is typical for pressed or released buttons. Also see the “Multiply” section
below.

Touch/Release

The incoming MIDI message(s) causes a change in the touched/released status of the
destination parameter. A non zero value means touched; a value of 0 means released.
The messages are displayed and entered in the same way as the Value Change field (see
the “Value Change” section above).

Note: This only applies to the Track assignment class and parameters that can be
automated.

Min/Max

Defines the minimum and maximum range for incoming values represented by Lo7
and Hi7. Typically, the full range of 0–127 is used, but some control surfaces may use the
same message with different value ranges for different controls (CM Labs Motor Mix, for
example).

Format

Defines the way negative values are encoded in the 7-bit portions sent over MIDI. You
can choose between the following options:
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Unsigned—No negative values are possible. The full 7 or 14 bit range is treated as a
positive number. This results in a value range of 0 to 127 or 0 to 16383.

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2's complement—If the most significant bit is set, the value is negative. To obtain the
absolute value, invert all bits and add 1. This results in a value range of –128 to 127 or
–8192 to 8191.

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1's complement—If the most significant bit is set, the value is negative. To set the
absolute value, invert all bits. Note that this allows two possible encoding values for
zero. This results in a value range of –127 to 127 or –8191 to 8191.

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Sign Magnitude—If the most significant bit is set, the value is negative. To set the
absolute value, clear the most significant bit. Note that this allows two possible
encoding values for zero. This results in a value range of –127 to 127 or –8191 to 8191.

The appropriate format that should be used is usually documented in your control
surface user manual. If unavailable, check the control surface manufacturer’s website,
or contact them via phone.

Multiply

Allows the incoming value to be scaled. Especially useful for button presses that have a
value of 1. Examples: to set the automation mode to Write, set Multiply to 4.00 and
Mode to Direct. To decrement a parameter by 1 with a button press, set Multiply to

1.00 and Mode to Relative. The 1 and –1 menu items in the combo box’s menu

conveniently enter the most commonly used values of 1 and –1

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